1. Field of the Invention
The present invention relates to orthopaedic implants, and, more particularly, to articulating bearing surfaces for orthopaedic implants.
2. Description of the Related Art
Orthopaedic implants used to reconstruct a joint of a patient typically include two implant halves with each implant half defining an articulating bearing surface. For example, an orthopaedic knee implant includes a proximal component which is placed within the femur and a distal component which is placed within the tibia. The proximal component typically includes a metallic articulating bearing surface which pivots on a non-metallic articulating bearing surface defined by the tibial knee component. The non-metallic bearing surface may be formed from a block of ultra-high molecular weight polyethylene (UHMWPE) which is machined to define the articulating bearing surface. The non-metallic bearing surface is attached to and carried by a tibial tray, which in turn is affixed to a stem inserted within the intramedullary canal (IM) of the tibia.
It is known to irradiate a bearing surface constructed from UHMWPE to crosslink the plastic material and improve the wear properties. The bearing surface is formed to a final shape and the entire bearing surface is irradiated. The penetration of the radiation depends upon factors such as the radiation energy, shape of the bearing surface, etc.